1/* 2 * Copyright (C) 2004-2007, 2009 Internet Systems Consortium, Inc. ("ISC") 3 * Copyright (C) 2003 Internet Software Consortium. 4 * 5 * Permission to use, copy, modify, and/or distribute this software for any 6 * purpose with or without fee is hereby granted, provided that the above 7 * copyright notice and this permission notice appear in all copies. 8 * 9 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH 10 * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY 11 * AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT, 12 * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM 13 * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE 14 * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR 15 * PERFORMANCE OF THIS SOFTWARE. 16 */ 17 18/* $Id: hash.c,v 1.13.332.3 2009/05/07 23:47:12 tbox Exp $ */ 19 20/*! \file 21 * Some portion of this code was derived from universal hash function 22 * libraries of Rice University. 23\section license UH Universal Hashing Library 24 25Copyright ((c)) 2002, Rice University 26All rights reserved. 27 28Redistribution and use in source and binary forms, with or without 29modification, are permitted provided that the following conditions are 30met: 31 32 * Redistributions of source code must retain the above copyright 33 notice, this list of conditions and the following disclaimer. 34 35 * Redistributions in binary form must reproduce the above 36 copyright notice, this list of conditions and the following 37 disclaimer in the documentation and/or other materials provided 38 with the distribution. 39 40 * Neither the name of Rice University (RICE) nor the names of its 41 contributors may be used to endorse or promote products derived 42 from this software without specific prior written permission. 43 44 45This software is provided by RICE and the contributors on an "as is" 46basis, without any representations or warranties of any kind, express 47or implied including, but not limited to, representations or 48warranties of non-infringement, merchantability or fitness for a 49particular purpose. In no event shall RICE or contributors be liable 50for any direct, indirect, incidental, special, exemplary, or 51consequential damages (including, but not limited to, procurement of 52substitute goods or services; loss of use, data, or profits; or 53business interruption) however caused and on any theory of liability, 54whether in contract, strict liability, or tort (including negligence 55or otherwise) arising in any way out of the use of this software, even 56if advised of the possibility of such damage. 57*/ 58 59#include <config.h> 60 61#include <isc/entropy.h> 62#include <isc/hash.h> 63#include <isc/mem.h> 64#include <isc/magic.h> 65#include <isc/mutex.h> 66#include <isc/once.h> 67#include <isc/random.h> 68#include <isc/refcount.h> 69#include <isc/string.h> 70#include <isc/util.h> 71 72#define HASH_MAGIC ISC_MAGIC('H', 'a', 's', 'h') 73#define VALID_HASH(h) ISC_MAGIC_VALID((h), HASH_MAGIC) 74 75/*% 76 * A large 32-bit prime number that specifies the range of the hash output. 77 */ 78#define PRIME32 0xFFFFFFFB /* 2^32 - 5 */ 79 80/*@{*/ 81/*% 82 * Types of random seed and hash accumulator. Perhaps they can be system 83 * dependent. 84 */ 85typedef isc_uint32_t hash_accum_t; 86typedef isc_uint16_t hash_random_t; 87/*@}*/ 88 89/*% isc hash structure */ 90struct isc_hash { 91 unsigned int magic; 92 isc_mem_t *mctx; 93 isc_mutex_t lock; 94 isc_boolean_t initialized; 95 isc_refcount_t refcnt; 96 isc_entropy_t *entropy; /*%< entropy source */ 97 unsigned int limit; /*%< upper limit of key length */ 98 size_t vectorlen; /*%< size of the vector below */ 99 hash_random_t *rndvector; /*%< random vector for universal hashing */ 100}; 101 102static isc_mutex_t createlock; 103static isc_once_t once = ISC_ONCE_INIT; 104static isc_hash_t *hash = NULL; 105 106static unsigned char maptolower[] = { 107 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 108 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f, 109 0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 110 0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f, 111 0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27, 112 0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f, 113 0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 114 0x38, 0x39, 0x3a, 0x3b, 0x3c, 0x3d, 0x3e, 0x3f, 115 0x40, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67, 116 0x68, 0x69, 0x6a, 0x6b, 0x6c, 0x6d, 0x6e, 0x6f, 117 0x70, 0x71, 0x72, 0x73, 0x74, 0x75, 0x76, 0x77, 118 0x78, 0x79, 0x7a, 0x5b, 0x5c, 0x5d, 0x5e, 0x5f, 119 0x60, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67, 120 0x68, 0x69, 0x6a, 0x6b, 0x6c, 0x6d, 0x6e, 0x6f, 121 0x70, 0x71, 0x72, 0x73, 0x74, 0x75, 0x76, 0x77, 122 0x78, 0x79, 0x7a, 0x7b, 0x7c, 0x7d, 0x7e, 0x7f, 123 0x80, 0x81, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87, 124 0x88, 0x89, 0x8a, 0x8b, 0x8c, 0x8d, 0x8e, 0x8f, 125 0x90, 0x91, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97, 126 0x98, 0x99, 0x9a, 0x9b, 0x9c, 0x9d, 0x9e, 0x9f, 127 0xa0, 0xa1, 0xa2, 0xa3, 0xa4, 0xa5, 0xa6, 0xa7, 128 0xa8, 0xa9, 0xaa, 0xab, 0xac, 0xad, 0xae, 0xaf, 129 0xb0, 0xb1, 0xb2, 0xb3, 0xb4, 0xb5, 0xb6, 0xb7, 130 0xb8, 0xb9, 0xba, 0xbb, 0xbc, 0xbd, 0xbe, 0xbf, 131 0xc0, 0xc1, 0xc2, 0xc3, 0xc4, 0xc5, 0xc6, 0xc7, 132 0xc8, 0xc9, 0xca, 0xcb, 0xcc, 0xcd, 0xce, 0xcf, 133 0xd0, 0xd1, 0xd2, 0xd3, 0xd4, 0xd5, 0xd6, 0xd7, 134 0xd8, 0xd9, 0xda, 0xdb, 0xdc, 0xdd, 0xde, 0xdf, 135 0xe0, 0xe1, 0xe2, 0xe3, 0xe4, 0xe5, 0xe6, 0xe7, 136 0xe8, 0xe9, 0xea, 0xeb, 0xec, 0xed, 0xee, 0xef, 137 0xf0, 0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7, 138 0xf8, 0xf9, 0xfa, 0xfb, 0xfc, 0xfd, 0xfe, 0xff 139}; 140 141isc_result_t 142isc_hash_ctxcreate(isc_mem_t *mctx, isc_entropy_t *entropy, 143 unsigned int limit, isc_hash_t **hctxp) 144{ 145 isc_result_t result; 146 isc_hash_t *hctx; 147 size_t vlen; 148 hash_random_t *rv; 149 hash_accum_t overflow_limit; 150 151 REQUIRE(mctx != NULL); 152 REQUIRE(hctxp != NULL && *hctxp == NULL); 153 154 /* 155 * Overflow check. Since our implementation only does a modulo 156 * operation at the last stage of hash calculation, the accumulator 157 * must not overflow. 158 */ 159 overflow_limit = 160 1 << (((sizeof(hash_accum_t) - sizeof(hash_random_t))) * 8); 161 if (overflow_limit < (limit + 1) * 0xff) 162 return (ISC_R_RANGE); 163 164 hctx = isc_mem_get(mctx, sizeof(isc_hash_t)); 165 if (hctx == NULL) 166 return (ISC_R_NOMEMORY); 167 168 vlen = sizeof(hash_random_t) * (limit + 1); 169 rv = isc_mem_get(mctx, vlen); 170 if (rv == NULL) { 171 result = ISC_R_NOMEMORY; 172 goto errout; 173 } 174 175 /* 176 * We need a lock. 177 */ 178 result = isc_mutex_init(&hctx->lock); 179 if (result != ISC_R_SUCCESS) 180 goto errout; 181 182 /* 183 * From here down, no failures will/can occur. 184 */ 185 hctx->magic = HASH_MAGIC; 186 hctx->mctx = NULL; 187 isc_mem_attach(mctx, &hctx->mctx); 188 hctx->initialized = ISC_FALSE; 189 result = isc_refcount_init(&hctx->refcnt, 1); 190 if (result != ISC_R_SUCCESS) 191 goto cleanup_lock; 192 hctx->entropy = NULL; 193 hctx->limit = limit; 194 hctx->vectorlen = vlen; 195 hctx->rndvector = rv; 196 197 if (entropy != NULL) 198 isc_entropy_attach(entropy, &hctx->entropy); 199 200 *hctxp = hctx; 201 return (ISC_R_SUCCESS); 202 203 cleanup_lock: 204 DESTROYLOCK(&hctx->lock); 205 errout: 206 isc_mem_put(mctx, hctx, sizeof(isc_hash_t)); 207 if (rv != NULL) 208 isc_mem_put(mctx, rv, vlen); 209 210 return (result); 211} 212 213static void 214initialize_lock(void) { 215 RUNTIME_CHECK(isc_mutex_init(&createlock) == ISC_R_SUCCESS); 216} 217 218isc_result_t 219isc_hash_create(isc_mem_t *mctx, isc_entropy_t *entropy, size_t limit) { 220 isc_result_t result = ISC_R_SUCCESS; 221 222 REQUIRE(mctx != NULL); 223 INSIST(hash == NULL); 224 225 RUNTIME_CHECK(isc_once_do(&once, initialize_lock) == ISC_R_SUCCESS); 226 227 LOCK(&createlock); 228 229 if (hash == NULL) 230 result = isc_hash_ctxcreate(mctx, entropy, limit, &hash); 231 232 UNLOCK(&createlock); 233 234 return (result); 235} 236 237void 238isc_hash_ctxinit(isc_hash_t *hctx) { 239 isc_result_t result; 240 241 LOCK(&hctx->lock); 242 243 if (hctx->initialized == ISC_TRUE) 244 goto out; 245 246 if (hctx->entropy) { 247 result = isc_entropy_getdata(hctx->entropy, 248 hctx->rndvector, hctx->vectorlen, 249 NULL, 0); 250 INSIST(result == ISC_R_SUCCESS); 251 } else { 252 isc_uint32_t pr; 253 unsigned int i, copylen; 254 unsigned char *p; 255 256 p = (unsigned char *)hctx->rndvector; 257 for (i = 0; i < hctx->vectorlen; i += copylen, p += copylen) { 258 isc_random_get(&pr); 259 if (i + sizeof(pr) <= hctx->vectorlen) 260 copylen = sizeof(pr); 261 else 262 copylen = hctx->vectorlen - i; 263 264 memcpy(p, &pr, copylen); 265 } 266 INSIST(p == (unsigned char *)hctx->rndvector + 267 hctx->vectorlen); 268 } 269 270 hctx->initialized = ISC_TRUE; 271 272 out: 273 UNLOCK(&hctx->lock); 274} 275 276void 277isc_hash_init() { 278 INSIST(hash != NULL && VALID_HASH(hash)); 279 280 isc_hash_ctxinit(hash); 281} 282 283void 284isc_hash_ctxattach(isc_hash_t *hctx, isc_hash_t **hctxp) { 285 REQUIRE(VALID_HASH(hctx)); 286 REQUIRE(hctxp != NULL && *hctxp == NULL); 287 288 isc_refcount_increment(&hctx->refcnt, NULL); 289 *hctxp = hctx; 290} 291 292static void 293destroy(isc_hash_t **hctxp) { 294 isc_hash_t *hctx; 295 isc_mem_t *mctx; 296 297 REQUIRE(hctxp != NULL && *hctxp != NULL); 298 hctx = *hctxp; 299 *hctxp = NULL; 300 301 LOCK(&hctx->lock); 302 303 isc_refcount_destroy(&hctx->refcnt); 304 305 mctx = hctx->mctx; 306 if (hctx->entropy != NULL) 307 isc_entropy_detach(&hctx->entropy); 308 if (hctx->rndvector != NULL) 309 isc_mem_put(mctx, hctx->rndvector, hctx->vectorlen); 310 311 UNLOCK(&hctx->lock); 312 313 DESTROYLOCK(&hctx->lock); 314 315 memset(hctx, 0, sizeof(isc_hash_t)); 316 isc_mem_put(mctx, hctx, sizeof(isc_hash_t)); 317 isc_mem_detach(&mctx); 318} 319 320void 321isc_hash_ctxdetach(isc_hash_t **hctxp) { 322 isc_hash_t *hctx; 323 unsigned int refs; 324 325 REQUIRE(hctxp != NULL && VALID_HASH(*hctxp)); 326 hctx = *hctxp; 327 328 isc_refcount_decrement(&hctx->refcnt, &refs); 329 if (refs == 0) 330 destroy(&hctx); 331 332 *hctxp = NULL; 333} 334 335void 336isc_hash_destroy() { 337 unsigned int refs; 338 339 INSIST(hash != NULL && VALID_HASH(hash)); 340 341 isc_refcount_decrement(&hash->refcnt, &refs); 342 INSIST(refs == 0); 343 344 destroy(&hash); 345} 346 347static inline unsigned int 348hash_calc(isc_hash_t *hctx, const unsigned char *key, unsigned int keylen, 349 isc_boolean_t case_sensitive) 350{ 351 hash_accum_t partial_sum = 0; 352 hash_random_t *p = hctx->rndvector; 353 unsigned int i = 0; 354 355 /* Make it sure that the hash context is initialized. */ 356 if (hctx->initialized == ISC_FALSE) 357 isc_hash_ctxinit(hctx); 358 359 if (case_sensitive) { 360 for (i = 0; i < keylen; i++) 361 partial_sum += key[i] * (hash_accum_t)p[i]; 362 } else { 363 for (i = 0; i < keylen; i++) 364 partial_sum += maptolower[key[i]] * (hash_accum_t)p[i]; 365 } 366 367 partial_sum += p[i]; 368 369 return ((unsigned int)(partial_sum % PRIME32)); 370} 371 372unsigned int 373isc_hash_ctxcalc(isc_hash_t *hctx, const unsigned char *key, 374 unsigned int keylen, isc_boolean_t case_sensitive) 375{ 376 REQUIRE(hctx != NULL && VALID_HASH(hctx)); 377 REQUIRE(keylen <= hctx->limit); 378 379 return (hash_calc(hctx, key, keylen, case_sensitive)); 380} 381 382unsigned int 383isc_hash_calc(const unsigned char *key, unsigned int keylen, 384 isc_boolean_t case_sensitive) 385{ 386 INSIST(hash != NULL && VALID_HASH(hash)); 387 REQUIRE(keylen <= hash->limit); 388 389 return (hash_calc(hash, key, keylen, case_sensitive)); 390} 391